This invention relates to engine speed change control arrangements and, more particularly, to an arrangement for preventing load change shocks in an engine used to drive a vehicle.
In the U.S. Pat. No. 4,819,598, to Eckart Muller, issued Apr. 11, 1989, an arrangement is described for limiting the effect (by way of a time delay) of accelerator pedal commands in the region of the zero passage of the torque curve of the engine. This arrangement is based on the knowledge that the load change shocks which occur on load changes, i.e., on transition from engine braking operation to traction operation and vice versa, which shocks may lead to longitudinal oscillations of the vehicle known as jerking, have their origin in the sign inversion of the torque on transition from engine braking to traction and vice versa. Consequently, that application, in a manner different from the state of the art existing at the time, describes an arrangement for limiting the transmission of the accelerator pedal commands to the power control element only in load regions associated with the zero passage on the torque transmission curve. In systems of that type, limitation of the torque transmission curve region in which the effect of the accelerator pedal command is reduced is of interest particularly in view of the fact that, when the need arises, rapid acceleration of the vehicle must be possible.
The arrangement described in U.S. Pat. No. 4,819,598 operates electronically and requires storage of the engine performance characteristics so that, generally speaking, it can be utilized only in vehicles with electronic engine control. The commonly-assigned U.S. patent application of Eckart Muller and Richard Dorenkamp, U.S. Ser. No. 206,874, filed June 9, 1988, also describes an engine control arrangement which specifically concerns the fuel injection pump of the engine. That arrangement includes a valve which is actuated only at the start of accelerator pedal movement out of the zero load position during a predefined time span, providing a limitation on the fuel quantity reaching the injection nozzle in approximately the zero load demand region of the engine operation.
Although the arrangement described in application Ser. No. 206,874 operates by hydraulic devices, a mechanically driven actuating device for the power control element of an internal combustion engine is known from German Offenlegungsschrift No. 36 32 035. In that device, a gas control cable contains a tension spring ahead of a swivelling lever whose motions are coupled with those of the power control element and a pneumatic piston-cylinder arrangement following the swivelling lever. In addition, the end of the gas control cable is connected to the piston bearing through a tension spring. The piston-cylinder arrangement defines pressure chambers on both sides of the piston, which at piston positions corresponding to low engine outputs are connected only by a throttle bore, but at larger engine outputs are connected through a practically throttle-free bypass. This known arrangement does not provide for individual adjustment with respect to the zero passage position of the torque transmission curve of the internal combustion engine.